High-performance absorbent structure

ABSTRACT

Disclosed is an absorbent structure having wet integrity higher than about 4.0 kN/gsm, softness higher than 8.0/J, pliability higher than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid. The structure includes an upper ply having an upper fluid receiving surface and a lower surface and including (i) a top stratum including synthetic matrix fibers bonded with a binder, the matrix fibers having length from about 2 to about 15 mm; (ii) a middle stratum in fluid communication with the top stratum, the middle stratum including natural fibers, superabsorbent particles and a binder; and (iii) a bottom stratum in fluid communication with the middle stratum, the bottom stratum including natural fibers and a binder. The structure also includes a lower ply in fluid communication with the upper ply, the lower ply having an upper surface and a lower surface and including at least one stratum including natural fibers, superabsorbent polymer particles, and a binder, wherein the lower surface of the upper ply has a surface area less than about 80% of the upper surface area of the lower ply.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119, based on U.S.Provisional Application Ser. No. 60/116,036, filed Jan. 11, 1999, theentire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to high-capacity, thin and highlyconformable absorbent structures, useful in absorbent articles includingbaby diapers, adult incontinence products, sanitary napkins and thelike. More particularly, the present invention relates to absorbentstructures containing matrix fibers, binders and superabsorbentpolymers, the structure having an x-directional fluid storage profile.

BACKGROUND OF THE INVENTION

Absorbent structures are important in a wide range of disposableabsorbent articles including baby diapers, adult incontinence products,sanitary napkins and the like.

These and other absorbent articles are generally provided with anabsorbent core to receive and retain body liquids. The absorbent core isusually sandwiched between a liquid pervious topsheet, whose function isto allow the passage of fluid to the core and a liquid imperviousbacksheet whose function is to contain the fluid and to prevent it frompassing through the absorbent article to the garment of the wearer ofthe absorbent article.

An absorbent core for diapers and adult incontinence pads frequentlyincludes fibrous batts or webs constructed of defiberized, loose,fluffed, hydrophilic, cellulosic fibers. The core may also includesuperabsorbent polymer (“SAP”) particles, granules, flakes or fibers(collectively “particles”).

In recent years, market demand for an increasingly thinner and morecomfortable absorbent article has increased. Such an article may beobtained by decreasing the thickness of the diaper core, by increasingthe amount of SAP particles, and by calendaring or pressing the core toreduce caliper and hence, increase density.

However, higher density cores do not absorb liquid as rapidly as lowerdensity cores because densification of the core results in a smallereffective pore size. Accordingly, to maintain suitable liquidabsorption, it is necessary to provide a low-density layer having alarger pore size above the high-density absorbent core to increase therate of uptake of liquid discharged onto the absorbent article. Thelow-density layer is typically referred to as an acquisition layer.Multiple layer absorbent core designs involve a more complicatedmanufacturing process.

The storage layer portion of a disposable diaper for example, isgenerally formed in place, during the converting process, from loose,fluffed cellulose. Such cellulose material is generally not available inpreformed sheet form because it exhibits insufficient web strength,owing to its lack of interfiber bonding or entanglement, to be unwoundor unfestooned directly onto and handled in absorbent pad-makingequipment.

Some absorbent articles such as ultra-thin feminine napkins aregenerally produced from roll-goods based nonwoven material. Such a rollof preformed absorbent core material is unwound directly as feedstockinto the absorbent article converting equipment without thedefiberization step normally required for fluff-based products, such asdiapers and incontinence pads. The nonwoven web is typically bonded orconsolidated in a fashion that gives it sufficient strength to behandled during the converting process. Absorbent structures made fromsuch nonwoven webs may also contain SAP particles. However, theseabsorbent structures are often inefficient in cases where a demand isfor acquisition and absorption of high amounts or a surge of bodyfluids. In these cases, a single sheet absorbent material often is notsufficient to fully utilize the absorbent core because the liquid is notdistributed in the structure along the length of the absorbent core. Asa result, regions of the absorbent core remain unused.

The web consolidation mechanism used in the roll-goods approach tomaking preformed cores provides strength and dimensional stability tothe web. Such mechanisms include latex bonding, bonding withthermoplastic or bicomponent fibers or thermoplastic powders,hydroentanglement, needlepunching, carding or the like. However, suchbonded materials provide a relatively stiff core which often does notconform well to the shape of the human body, especially in thosesituations where there is a demand for good fit to acquire and containhigh volumes of body fluids.

Pliability and softness of the absorbent core are necessary to ensurethat the absorbent core can easily conform itself to the shape of thehuman body or to the shape of a component (for example another absorbentply) of the absorbent article adjacent to it. This in turn prevents theformation of gaps and channels between the absorbent article and thehuman body or between various parts of the absorbent article, whichmight otherwise cause undesired leaks in the absorbent article.

Integrity of the absorbent core is necessary to ensure that theabsorbent core does not deform and exhibit discontinuities during itsuse by a consumer. Such deformations and discontinuities can lead to adecrease in overall absorbency and capacity, and an increase inundesired leakages. Prior absorbent structures have been deficient inone or more of pliability, integrity, profiled absorbency and capacity.For example, a conventional (fluff pulp) core has good conformabilitybecause of its high pliability and softness but at the same time it maydisintegrate easily during use, due to its poor integrity. As anotherexample, certain bonded cores, such as airlaid cores made from cellulosefluff pulp densified to greater than 0.35 g/cc have good dry integrity,but have poor wet integrity and poor conformablity.

The absorbent materials described herein exhibit a superior combinationof x-directional storage profile, conformability and integrity. Thiscombination provides improved fluid acquisition and containment as wellas increased comfort and reduced leakage potential. Further, theimproved integrity of the disclosed absorbent materials reduces the riskof deformation of the absorbent material and better protects the surfaceof the skin of the user from exposure to liquid.

SUMMARY OF THE INVENTION

The present invention relates to an absorbent structure having wetintegrity higher than about 4.0 kN/gsm, softness higher than 8.0/J,pliability higher than about 70/N, and providing a substantially dryliquid-accepting surface after receiving a quantity of liquid. Thestructure includes an upper ply having an upper fluid receiving surfaceand a lower surface and including a top stratum including syntheticmatrix fibers bonded with a binder, the matrix fibers having length fromabout 2 to about 15 mm; a middle stratum in fluid communication with thetop stratum, the middle stratum including natural fibers, superabsorbentparticles and a binder; and a bottom stratum in fluid communication withthe middle stratum, the bottom stratum including natural fibers and abinder. The structure also includes a lower ply in fluid communicationwith the upper ply, the lower ply having an upper surface and a lowersurface and including at least one stratum including natural fibers,superabsorbent polymer particles, and a binder, wherein the lowersurface of the upper ply has a surface area less than about 80% of theupper surface area of the lower ply.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1a-1 d depict an absorbent structure of the invention comprisingan upper absorbent ply and a lower absorbent ply.

FIG. 2 is a schematic representation of a modified clamp used in aGurley tester.

FIG. 3 depicts a schematic representation of the apparatus for measuringsoftness.

DETAILED DESCRIPTION OF THE INVENTION

All references cited in this application are hereby fully incorporatedby reference. In case of conflict in terminology, the present disclosurecontrols.

The present invention includes an absorbent structure of at least twoplies of bonded absorbent material, wherein the plies are in fluidcommunication with each other. With reference to FIG. 1a, the structureincludes: (a) a shorter, upper ply 2 having three strata 6, 8 and 10;and (b) a longer, lower absorbent ply 4. In general, the surface area ofthe bottom surface of upper ply 2 is less than 80% of the surface areaof the upper surface of lower ply 4. This arrangement has an advantageover single-ply core structures by allowing for better containment andusage of the absorbent material during use of the absorbent article bythe user.

With reference to FIG. 1b, the advantage obtained by providing a two plystructure as described above, is that the fluid discharge from the humanbody occurs mainly over the frontal 16 and central 18 region of theabsorbent core. The present invention places more of the absorbentcapacity in the region where the liquid discharge insults the core.Further, the overall density of upper ply 2 is lower than the overalldensity of lower ply 4. This difference in densities allows for improvedfluid acquisition and rewet performance since liquid is drawn from theupper ply to the lower ply due to the capillary tension gradient betweenthe plies.

Both the upper ply and the lower ply contain binders and SAP particles.In general, the upper ply contains a higher concentration of SAPparticles than the lower ply. The lower ply contains at least 30% SAPparticles by weight of the lower ply. A high concentration of SAPparticles provides high absorbent capacity and liquid retention withinthe absorbent structure. On the other hand, a lower concentration of SAPparticles in the upper ply is advantageous, because gel blocking (whichwould lead to the inhibition of fluid flow downward to the lower ply) inthis part of the absorbent structure may be avoided.

In the present invention, the SAP particles may be dispersedhomogeneously within the matrix of fibers and binders. Alternatively,the SAP particles may be placed in discrete locations or zones withinthe structure. For example, with reference to FIGS. 1c and 1 d the SAPparticles may be placed in narrow lanes 20 along the absorbent core. Thelanes of SAP particles are then separated by lanes of fibers 22 bondedwith a binder. Such a discrete placement of SAP particles allows forbetter containment of the particles, facilitates flow of liquid in theZ-direction, because of the presence of areas with little or no SAP, andallows for easier flow and wicking of the fluid along the length of thecore (x-direction). The areas with little or no SAP particles may beadditionally densified to improve integrity and create higher capillarytension within smaller pores. Preferably, such densification takes placealong the length of the absorbent structure. The pliability of such amaterial can thus be maintained, particularly in the y-direction (acrossthe core).

With reference to FIG. 1a, a schematic cross-section of a preferredabsorbent structure of the present invention is shown. The absorbentstructure includes upper ply 2 and lower ply 4. Upper ply 2 includesthree strata 6, 8 and 10 and is preferably made as a unitary airlaidstructure. Upper stratum 6 is a low density acquisition layer includingfrom between 50 to 99% by weight of wettable synthetic fibers,preferably from 75 to 90% synthetic fibers, the balance of the stratumbeing binder material. Due to its relatively low density, large poresize, and lower wettability than that of the layers below, top stratum 6has essentially no aqueous liquid wicking capability. Fluid is easilywicked from it downward to the more wettable and smaller-pore, higherdensity strata below. Top stratum 6 includes synthetic fibers having athickness of from 2 to 30 denier, preferably of from 6 to 15 denier. Thesynthetic fibers have a length of from 2 to 15 mm, preferably of from 4to 12 mm. Optionally, the fibers may be crimped and may have a varietyof cross-sectional shapes. Top stratum 8 of upper ply 2 has a basisweight of from 20 to 120 gsm (grams per square meter), preferably offrom 30 to 60 gsm.

Middle stratum 8 of upper ply 2 is composed predominantly of naturalfibers and also contains SAP particles. The content of SAP particles inthis stratum is from 5 to 60% by weight of upper ply 2, preferably from20 to 40% by weight of the upper ply. The basis weight of the middlestratum of the upper ply is from 50 to 1000 gsm (grams per squaremeter), preferably from 80 to 300 gsm. The middle stratum of the upperply may be bonded with any suitable type of binder. Preferably, thebinder is a bicomponent thermoplastic fiber, present in middle stratum 8an amount of from 1 to 15% of the basis weight of the middle stratum andpreferably from 5 to 10%.

Bottom stratum 10 of upper ply 2 includes bonded, natural fibers. Thislayer may be for example a wet-laid cellulose tissue bonded with binderstypically used in papermaking processes. Optionally, this tissue mayalso be impregnated for example with one or more heat-activated binders,such as bicomponent binder fibers, which would be activated during theweb curing process and would then bond the tissue together with thestrata above it. The bottom stratum of the upper ply may also be formedduring the formation of the upper ply, for example as a bonded airlaidlayer. Any suitable binder may be used to bind stratum 10. If, forexample, a binder fiber is employed for this purpose, it is present inan amount of from 3 to 15% of the basis weight of bottom stratum 10, andpreferably from 5 to 10%. Other binders, such as latex-based binders orwater-dispersible bonding agents used commonly in wet papermakingprocesses are also suitable. Stratum 10 has a basis weight of from 10 to200 gsm, preferably from 15 to 90 gsm.

Lower absorbent ply 4 is a bonded structure of natural fibers and SAPparticles. In general, the amount (in weight %) of SAP particles inlower ply 4 is higher than the amount of SAP particles in upper ply 2.The lower ply contains from 30 to 80% SAP particles by weight, andpreferably from 40 to 60%.

Optionally, lower ply 4 may contain a top stratum 12, including bondednatural fibers for better containment of SAP particles in the stratum 13or strata below it. Any suitable binder can be used to bond thestructure of the lower ply. If, for example, a binder fiber is used, itis present in an amount of from 1 to 8% by weight of the lower ply,preferably from 2 to 5%.

In general, lower ply 4 has a higher overall density than the overalldensity of upper ply 2. The density of the lower ply may be from 0.1 to0.35 g/cc (grams per cubic centimeter), preferably from 0.15 to 0.25g/cc. Densities higher than 0.35 g/cc are undesirable due to reducedconformability found with such dense structures. The basis weight of thelower ply may range from 100 to 1000 gsm, preferably from 150 to 400gsm.

The absorbent structure of the invention can be made by various formingmethods and by using various raw materials such as natural and syntheticfibers, various types of SAP particles, and different kinds of binders,including fibers, powders or liquids.

Examples of the types of natural fibers which can be used in the presentinvention include: fluffed cellulose fibers prepared from cotton,softwood and/or hardwood pulps, straw, keaf fibers, cellulose fibersmodified by chemical, mechanical and/or thermal treatments, keratinfibers such as fibers obtained from feathers, as well as man-made staplefibers made with natural polymers such as cellulose, chitin, andkeratin. Examples of suitable synthetic matrix fibers includepolyethylene, polypropylene, polyester, including polyesterterephthalate (PET), polyamide, cellulose acetate and rayon fibers.Certain hydrophobic synthetic fibers, such as polyolefins, should besurface treated with surfactant to improve wettability.

U.S. Pat. Nos. 5,147,343; 5,378,528; 5,795,439; 5,807,916; and5,849,211, which describe various superabsorbent polymers and methods ofmanufacture are hereby incorporated by reference. Examples of the typesof SAP particles which may be used in this invention, includesuperabsorbent polymers in their particulate form such as irregulargranules, spherical particles, staple fibers and other elongatedparticles. The term “superabsorbent polymer” or “SAP” refers to anormally water-soluble polymer, which has been cross-linked. There areknown methods of making water-soluble polymers such as carboxylicpolyelectrolytes to create hydrogel-forming materials, now commonlyreferred to as superabsorbents or SAPs, and it is well known to use suchmaterials to enhance the absorbency of disposable absorbent articles.There are also known methods of crosslinking carboxylatedpolyelectrolytes to obtain superabsorbent polymers. SAP particles usefulin the practice of this invention are commercially available from anumber of manufacturers, including Dow Chemical (Midland, Mich.),Stockhausen (Greensboro, N.C.), and Chemdal (Arlington Heights, Ill.).One conventional granular superabsorbent polymer is based onpoly(acrylic acid) which has been crosslinked during polymerization withany of a number of multi-functional co-monomer crosslinking agents, asis well known in the art. Examples of multifunctional crosslinkingagents are set forth in U.S. Pat. Nos. 2,929,154; 3,224,986; 3,332,909;and 4,076,673. Other water-soluble polyelectrolyte polymers are known tobe useful for the preparation of superabsorbents by crosslinking, thesepolymers include carboxymethyl starch, carboxymethyl cellulose, chitosansalts, gelatin salts, etc. They are not, however, commonly used on acommercial scale to enhance absorbency of disposable absorbent articles,primarily due to lower absorbent efficiency or higher cost.

Examples of binders useful in the absorbent structure of the presentinvention include polymeric binders in a solid or liquid form. The term“polymeric binder” refers to any compound capable of creating interfiberbonds between matrix fibers to increase the integrity of the ply. At thesame time, the binder may optionally bind fibers and SAP particles toeach other. For example, a dispersion of natural or syntheticelastomeric latex may be used as a binder. Examples of suitable latexbinders are polymers and copolymers of acrylate, vinyl acetate andstyrene-butadiene. Thermoplastic fibers or powder, which are well knownin the art, are also commonly used to provide bonding upon heating ofthe absorbent structure to the melting point of the thermoplastic fiberor powder. Other binders, which can be used for stabilizing theabsorbent structure of the present invention, include bonding agentsused to bond cellulose fibers. These agents include polymers dispersedin water, which are cured after application to the fibrous web andcreate bonds between fibers or between fibers and SAP particles.Examples of such agents include various cationic starch derivatives andsynthetic cationic polymers containing crosslinkable functional groupssuch as polyamide-polyamine epichlorohydrin adducts, cationic starch,dialdehyde starch and the like. Any combination of the above-describedpolymeric binders may be used for stabilizing the structure of thepresent invention. In one embodiment, the binder in the invention is abinding fiber, which comprises less than about 10% by weight of the SAPparticles. In another example of the invention, the binder fiberscomprise less than about 7% by weight of the absorbent structure.

As used herein, “integrity” is a measure of the tensile strength of afibrous sheet, normalized for unit basis weight and is expressed inunits (milliNewtons, Mn) of x-directional force required to break a 1inch wide sample of the sheet per normalized basis weight of 1 gsm. Inorder to measure Wet Integrity (wet tensile strength) of an absorbentcore or a commercial absorbent product, the following procedure is used:

1. 1 inch×4 inch samples are prepared. For samples with an obviousmachine direction and cross direction, the 4-inch dimension is cut inthe machine direction.

2. Remove any removable plastic backsheet, coverstock or syntheticacquisition material, leaving only the core.

3. Weigh sample. Apply 0.9% saline solution, in an amount equal to twicethe sample weight, to the center of the sample using pipette or spraybottle (Example: sample weighs 1.00 g. Apply 2.00 g saline solution fortotal of 3.00 g).

4. Insert sample into Tensile Tester (for example a Thwing-Albert LT-150Universal Materials Tester, default software settings used for test) byplacing in pressurized clamps.

5. Start test.

6. When test is finished, record results displayed. These resultsinclude Force at Peak, Elongation at Peak, Maximum Elongation, Energy atPeak, and Energy at Maximum.

The Wet Integrity as used herein is defined as the Force at Peak asmeasured by using the above procedure. The Wet Integrity of theabsorbent structures of the present invention are higher than 4.0mN/gsm, and preferably higher than 6.0 mN/gsm.

The softness of the absorbent structure is an important factorcontributing to the overall conformability of the structure. As usedherein, “softness” is the inverse of the amount of energy necessary tocompress a sheet, in this case the sheet being the absorbent structure.The greater the amount of energy necessary to compress a sheet, the lesssoft it is. To measure softness of the core, the following procedure (amodified compression test) is used:

1. Prepare samples by cutting three 4 inch×8 inch pieces (if sample is adiaper, cut from the thicker section of diaper (if thickness is notuniform). For samples with obvious machine direction and crossdirection, cut 8-inch dimension in machine direction.

2. Allow plastic backsheet and coverstock material to remain on sample(applies to commercial diaper samples). If testing prototype coresamples, apply plastic backsheet, Exxon EMB-685 polyethylene film, tobottom of sample and coverstock, 15 gsm Avgol spunbond polypropylene, totop of sample (same size as sample, adhered with a small amount of sprayadhesive).

3. Program modified compression test (for example, a Thwing-AlbertLT-150 Universal Materials Tester): Compression test using followingnon-default settings: Break Detection Method=% Drop/Displacement, BreakValue=% Drop=50, Distance Traps=0.3 in./0.5 in./0.7 in., Units:Distance/Displacement=inches; Force=grams, Test speed=1 in./min. Allother settings left at defaults.

4. Insert sample into Tensile Tester using custom clamps as depicted inFIG. 3. Sample is inserted on its edge, such that it will be compressedin the y-direction (4-inch direction), having 1 inch on both edgeswithin the custom clamps, thus leaving a 2-inch gap.

5. Start test.

6. When deflection exceeds 0.7 inch, push down on top pressurized clampto simulate a sample break and stop the test (does not affect testresults). Record results displayed. These results include Force at Peak,Deflection at Peak, Maximum Deflection, Energy at Peak, and Energy atMaximum Deflection, and Force at Distance Traps.

The value, which is used to calculate the softness, is Energy at MaximumDeflection, which is expressed in Joules. Energy of Maximum Deflection,E_(d max), is calculated according to the following formula:

 E _(d max) _(d max) =^(d max) ∫F d _(d)

where E_(d max) is Energy at Maximum Deflection, F is force at givendeflection, d, and d min and d max are the deflections at the start ofthe test and at the end of the test, respectively.

Softness, S, is defined here according to the following formula:

S=1/(Energy at Maximum Deflection).

The result, S, is expressed here in 1 per Joule, 1/J.

In general, Softness of the overall absorbent structure of the presentinvention should be higher than 8.0/J, preferably higher than 15/J.

The pliability of the absorbent structure is also an important factorcontributing to the overall conformability of the sheet. As used herein,“pliability” is the inverse of the amount of force necessary to bend asheet, in this case the sheet being the absorbent structure of theinvention. The greater the force necessary to bend the sheet, the lesspliable the sheet is.

Pliability can be measured by the following procedure, using a Gurleytester (Model 4171, Gurley Precision Instruments, Trey, N.Y.).

1. Cut sample to 1 inch×3.25 inch as accurately as possible. If there isa definite machine direction and cross direction, cut one sample in eachdirection and test each.

2. Fit custom clamp as shown in FIG. 3, over the original clamp providedwith the Gurley tester, and tighten smaller, upper thumbscrews to secure(see FIG. 2 illustrating the custom clamp for higher basis weight, loftysheets). The custom clamp was designed in such a way that it does notchange the thickness of the tested material, where the material isinserted into the clamp. If the thickness is changed as a result ofclamping then the properties of the structure are changed and theresults obtained by using the Gurley tester are affected. In the presentmethod, the clamp of FIG. 3 is used to eliminate such undesired effects.

3. Open the custom clamp adjustable plate by loosening longer, lowerthumbscrews. Place sample in clamp by sliding sample up until it justcontacts original clamp. There should be 2.0 inches of sample containedin the custom clamp.

4. Adjust height of custom clamp by loosening height adjustment screw onoriginal clamp. Adjust height so that a gap of 1.0 inch exists betweenthe point where the sample exits the custom clamp and the point wherethe sample will contact the lever arm.

5. Ensure that the remaining 0.25 inch of sample extends below the topof the lever arm. Ensure that lever arm is not moving. Press motorbutton to move sample towards lever arm. Continue pressing motor buttonuntil sample clears lever arm. While doing this, observe and note thehighest number reached on the scale. Repeat this in the oppositedirection.

6. Average the two values obtained. In the conversion chart on theapparatus, find the factor for a 1 inch wide×1.5 inch long sampledepending on the weight used and the distance the weight was placed fromthe center on the lever arm. A 1.0 inch×3.25 inch sample tested usingthe custom clamp corresponds to a 1.0 inch×1.5 inch sample testedwithout using the custom clamp. Without the custom clamp, 0.25 inch ofsample is in the original clamp, 0.25 inch extends below the top of thelever arm, and 1 inch is the gap between. Using the custom clamp, thesame 0.25-inch number in the custom clamp is used; the other 1.75-inchin the custom clamp secures the thicker sample in place. The same0.25-inch extends below the top of the lever arm and the same one-inchgap is in between.

7. Multiply the average reading on the scale by the appropriateconversion factor found on the chart.

The result is Stiffness, which is expressed in milligrams force, mg.Pliability, P, is defined here according to the following formula:

P=10⁶/9.81*Stiffness.

The result, P, is expressed here in 1 per Newton, 1/N. In general,Pliability of the entire absorbent structure of the present invention ishigher than 60/N, preferably higher than 80/N.

In the present invention, high levels of softness, pliability and wetintegrity have been achieved by applying one or a combination of thefollowing features in the preparation of an absorbent structure: byusing soft fibers, curled or crimped fibers, by applying soft bindersystems, such as for example fine or crimped binding fibers, elasticlatex binders or water-soluble bonding agents, by minimizing the amountsof binder, applying relatively low pressure during compaction beforecuring, and using relatively low pressure during the calandering of thesheet after it has been cured. In general, the density of the sheetafter compaction and/or calandering in the absorbent structures of theinvention should be lower than 0.35 g/cc, and preferably lower than 0.3g/cc.

In one embodiment of the invention, no carrier tissue sheet is used inthe web forming process. Such carrier tissue sheets are usually used andbecome an integral part of the structure. They increase the strength ofthe web but increase its stiffness.

In another embodiment of the invention, the amount of binding fiber inthe structure is less than 10% by weight of the structure. In anotherembodiment the amount of binding fiber is lower than 7% by weight of thestructure. Typically, higher amounts of binders are used which result inan absorbent structure of relatively high integrity but low pliability.

In another embodiment of the invention the softness and pliability ofthe structure is achieved by mechanical treatment of the entirestructure or of its component absorbent plies after formation of theabsorbent plies. Such mechanical treatments include microcreping,passing the web through the nip between grooved rolls and the like. Ingeneral, in these procedures some of the bonds within the structure aredisrupted and, as a result, the structure becomes more conformable.

The integrity of the absorbent structure of this invention is higherthan that of a conventional core made with only fluff and SAP powder andis sufficiently high to allow the sheet of the core to be used inconversion. In particular, the wet integrity of the absorbent structureof this invention is higher than that of conventional cores and ofairlaid cores made without binders. In one embodiment, the absorbentcore has a wet integrity greater than 4.0 mN/gsm. In another embodiment,the absorbent core has a wet integrity greater than 6.0 mN/gsm. In yetanother embodiment, the absorbent core has a wet integrity greater than8.0 mN/gsm. The wet integrity of conventional cores and airlaid coresmade without any binders is relatively low and is commonly below 4.0mN/gsm (see Table 1). In the conventional cores (formed in place),integrity is mainly dependent on mechanical entanglement of flufffibers. Since such a mechanical entanglement is due to in part to theamount of curl of the fibers , and this curl is lost at least to someextent when the material is wetted. The integrity of the conventionalcore is also decreased substantially in the wet state. In the case ofairlaid materials (such as described in U.S. Pat. Nos. 5,866,242 or5,916,670), which are made without any binders but are highly densified,the densified structures are held together mainly with the aid ofhydrogen bonds. However, such bonds are broken completely when thematerial is wetted and then the absorbent core becomes very weak.

The softness and pliability of the absorbent structure of the presentinvention are high enough that the material may conform easily to theshape of the human body or to the shape of a component (for exampleanother absorbent layer) of the absorbent article adjacent to it. In oneembodiment, the softness of the absorbent structure is higher than 8.0/Jand the pliability of the absorbent structure is higher than 60/N.

To further increase the levels of softness, pliability and wet integrityof the absorbent structure, the structure may be treated using variouschemical and/or mechanical processes. Without being bound by any theory,it is believed that, for a given composition of the absorbent structure,the desired level of softness, pliability, and wet integrity can beachieved with an appropriate ratio of bonded to unbonded structuralelements. If the number of bonds between the fibers or between thefibers and SAP particles is too small, then the wet integrity of thestructure is too low to achieve improved performance of the absorbentstructure during use. When the user moves then such a low-integritystructure may not withstand mechanical stresses and may produce cracksand other discontinuities, leading to poor liquid containment andsubsequent leaks. On the other hand, if the number of bonds in theabsorbent structure is too high, then pliability and softness are toolow and the structure becomes less conformable, degrading performancedue to formation of undesirable channels and gaps through which theliquid may freely flow and leak out of the absorbent article.

As exemplified below, the absorbent structure may be used in combinationwith a carrier such as cellulose tissue or a synthetic nonwoven. Theabsorbent structure may also be used in combination with other layers orstructures to form an absorbent structure.

In another preferred embodiment, the upper ply of the structure is usedseparately as an absorbent structure. The one ply structure exhibitshigh wet integrity, high softness and high pliability, and can be usedin a variety of applications requiring such attributes. Examples of suchapplications include disposable absorbent articles such as disposablediapers, sanitary pads, adult incontinence products and training pants.

The one ply absorbent structure can be made as set forth in the examplesrelating to the two-ply structures. Alternatively, the one ply structuremay be made using an airlaid machine employing three forming heads.Examples using such a machine are set forth below as Examples 8 to 11.

The invention is further described in the following non-limitingexamples.

In the following examples basis weights (in gsm) are set forth astargets. Actual basis weights obtained may vary by up to ±10%.

EXAMPLE 1

An absorbent structure was assembled by joining together upper ply(component A1) and lower ply (component B 1) described below. Bothabsorbent components were made by dry forming (or airlaying) on an M&Jpilot machine. The mechanical and absorbency properties of the structureare depicted in Tables 1, 3 and 4. The structure exhibited improvedperformance compared to the performance found with commercial structuresas described herein, due to the combination of profiled absorbency andappropriate levels of conformability and integrity.

Component A1. Two forming heads were used and they were fed with thesame composition and amount of raw materials. The product was laid on acarrier of 40 gsm Brand 6810 polyester (polyethylene terephthalate)nonwoven (PGI). This material constituted the top stratum of the upperply. The basis weights and compositions of the middle stratum and of thebottom stratum were the same, the basis weight being 160 gsm and thecomposition being 56.3% HPF fluff (Buckeye Technologies Inc., Memphis,Tenn.), 37.5% Z1049 SAP (Stockhausen, Greensboro, N.C.) and 6.2% T-255,2.8 dpf (denier per fiber) thermoplastic, bicomponent binder fiber(Kosa, Salisbury, N.C.). The sheet was calandered after curing (160° C.;1 min. dwell) with minimum pressure to a thickness of 3 mm.

Component B 1. The first forming head was fed with Foley Fluff (BuckeyeTechnologies) at 75 gsm and T-255 binder fiber (Kosa, Salisbury, N.C.)at 3 gsm. The formed layer was the middle stratum of the Lower Ply. Thetop stratum of the lower ply was formed by the second forming head,which was fed with Foley Fluff (Buckeye Technologies) at 55 gsm, T-255binder fiber (Kosa, Salisbury, N.C.) at 12 gsm, and SXM4750 SAP(Stockhausen, Greensboro, N.C.) at 215 gsm. The product was laid on acarrier, which was Duni Finner K1801 cellulose tissue (Duni, Kisa,Sweden). The carrier constituted the bottom stratum of the lower ply.The sheet was calandered after curing to a thickness of 2 mm.

The components were assembled by placing a 10×20 cm A1 sheet of materialover one end of a 10×40 cm B1 sheet of material. Measurements were madeat the end where the A1 and B 1 sections overlapped.

EXAMPLE 2

An absorbent structure was assembled by joining together Components A2and B2 described below. Both absorbent components were made by dryforming on an M&J pilot machine. In the resultant structure component A2is the upper ply and component B2 is the lower ply. The mechanical andabsorbency properties of the structure are depicted in Tables 1, 3 and4. The structure exhibited improved performance due to the combinationof profiled absorbency and appropriate levels of conformability andintegrity.

Component A2. The middle stratum of the Upper Ply was formed by feedingthe first forming head with HPF fluff (Buckeye Technologies, Memphis,Tenn.) at 40 gsm and 2.8 dpf T-255 binder fiber (Kosa, Salisbury, N.C.)at 2.5 gsm. The second head was used to form the top stratum of theupper ply. The second forming head was fed with HPF fluff (BuckeyeTechnologies, Memphis, Tenn.) at 100 gsm, Z1049 SAP (Stockhausen,Greensboro, N.C.) at 94 gsm, and 2.8 dpf T-255 binder fiber (Kosa,Salisbury, N.C.) at 13 gsm. The product was laid on a carrier, which was48 gsm Licontrol™ 381002 (polypropylene) nonwoven (Jacob-HolmIndustries, Soultz, France). This carrier constituted the top stratum ofthe upper ply. The product was calandered after curing with minimumpressure to a thickness of 3.0 mm.

Component B2. Two forming heads were used and they were fed with thesame composition and amount of raw materials. The product was laid on acarrier, which was Duni Finner K1801 cellulose tissue. The compositionof the overall component B2 having a basis weight of 378 gsm was 34.1%Foley Fluff (Buckeye Technologies), 57.1% SXM3950 SAP (Stockhausen,Greensboro, N.C.), and 4% T-255, 2.8 dpf binder fiber (Kosa, Salisbury,N.C.); the balance of the structure was a carrier tissue of 18 gsm. Thesheet was calandered after curing to a thickness of 2 mm.

EXAMPLE 3

An absorbent structure was assembled by joining together Components A3and B3 described below. Both absorbent components were made by dryforming on a DanWeb pilot machine. In the resultant structure ComponentA3 is the upper ply and Component B3 is the lower ply. The mechanicaland absorbency properties of the structure are depicted in Tables 1, 3and 4. The structure exhibited improved performance due to thecombination of profiled absorbency and appropriate levels ofconformability and integrity.

Component A3. The first forming head was fed with Foley Fluff (BuckeyeTechnologies, Memphis, Tenn.) at 60 gsm and 2.8 dpf T-255 binder fiber(Kosa, Salisbury, N.C.) at 10 gsm, to form the bottom stratum of theupper ply. The second head was used to form the middle stratum of theupper ply. The second head was fed with Foley Fluff at 98 gsm, SXM70 SAP(Stockhausen, Greensboro, N.C.) at 62.5 gsm, and 2.8 dpf T-255 binderfiber (Kosa, Salisbury, N.C.) at 19.5 gsm. The third head was fed withWellman 376×2 polyester fibers having thickness of 15 dpf and length of6 mm at 35 gsm. The top stratum of the upper ply thus formed was sprayedwith A-181 latex (Air Products, Allentown, Pa.) diluted to 10% solids at5 gsm. The sheet was calandered after curing with minimum pressure to athickness of 4.1 mm.

Component B3. One forming head was used and it was fed with ND416fluff(Weyerhaeuser, Tacoma, Wash.) at 128 gsm, SXM70 SAP (Stockhausen,Greensboro, N.C.) at 225 gsm and 2.8 dpf T-255 binder fiber (Kosa,Salisbury, N.C.) at 22 gsm. The product was laid on a Cellutissue 3024cellulose tissue carrier. The sheet was calandered after curing to athickness of 1.9 mm.

EXAMPLE 4

An absorbent structure was assembled by joining together Components A4and B4 described below. Both absorbent components were made by dryforming on a DanWeb pilot machine. In the resultant structure ComponentA4 is the upper ply and Component B4 is the lower ply. The mechanicaland absorbency properties of the structure are depicted in Tables 1, 3and 4. The structure exhibited improved performance due to thecombination of profiled absorbency and appropriate levels ofconformability and integrity.

Component A4. The first forming head was fed with Foley Fluff (BuckeyeTechnologies, Memphis, Tenn.) at 77.6 gsm and 2.8 dpf T-255 binder fiber(Kosa, Salisbury, N.C.) at 12.4 gsm, forming the bottom stratum of theupper ply. The second head was used to form the middle stratum of theupper ply. The second head was fed with Foley Fluff at 102 gsm, SP 1186SAP (Stockhausen, Greensboro, N.C.) at 130 gsm, and 2.8 dpf T-255 binderfiber (Kosa, Salisbury, N.C.) at 28 gsm. The third head was fed withWellman 376×2 polyester fibers having thickness of 15 dpf and length of6 mm, at 42 gsm. The top stratum of the Upper Ply thus formed wassprayed with A-124 latex (Air Products, Allentown, Pa.) diluted to 10%solids at 8 gsm. The sheet was calandered after curing with minimumpressure to a thickness of 5.7 mm.

Component B4. The first and second forming heads were fed with equalamounts of all components, that is with ND416 fluff (Weyerhaeuser,Tacoma, Wash.) at 37 gsm, SXM3950 SAP (Stockhausen, Greensboro, N.C.) at92.3 gsm and 2.8 dpf T-255 binder fiber (Kosa, Salisbury, N.C.) at 5gsm. The web thus formed became the bottom stratum of the lower ply.This stratum was laid on a Cellutissue 3024 cellulose tissue carrier.The third head was fed with ND416 fluff at 38.5 gsm and 2.8 dpf T-255binder fiber at 8.9 gsm, forming the top stratum of the lower ply. Thefinal sheet was calandered after curing to a thickness of 1.45 mm.

EXAMPLE 5

The structures of Examples 1, 2, 3 and 4 were analyzed for WetIntegrity, Softness and Pliability. The results obtained are summarizedin Table 1. In Table 1 are summarized also the results of the analysisof the absorbent cores of several commercial disposable infant diapers(samples A, B and C) and a sample of a high-density airlaid materialmade with fluff and SAP and without any binder (sample D). Determinationof basic structural parameters of the tested cores are shown in Table 2.The data in Table 1 demonstrate that the absorbent structures ofExamples 1, 2, 3 and 4 have much higher Wet Integrity than all the othertested commercial cores and much higher softness and pliability than thecore of sample D.

TABLE 1 Wet Integrity Absorbent Structure mN/gsm Softness, 1/JPliability, 1/N Example 1 5.2 8.9 72.9 Example 2 7.2 10.2 112.0 Example3 8.7 17.8 104.0 Example 4 7.0 10.6 105.2 Example A 0.8 10.1 175.5Example B 2.6 12.9 137.8 Example C 1.5 7.4 117.7 Example D 1.3 5.6 40.2

TABLE 2 Upper Lower Overall Overall Overall Upper Lower Assembled corecore average Upper Lower average Upper Lower average core width corewidth surface Basis Basis Basis core core core core core core × length ×length area Weight Weight Weight Density Density Density % % % Sample(cm × cm) (cm × cm) (cm²⁾ (gsm) (gsm) (gsm) (g/cc) (g/cc) (g/cc) SAP SAPSAP Example D  8 × 20 11 × 36 396 400 310 472 0.27 0.36 0.31 37.0 51.043.0 Example C 385 759 0.14 26.7 Example B 468 617 0.25 53.5 Example A360 649 0.26 43.4 Example 1 10 × 20 10 × 40 400 360 375 555 0.12 0.190.16 37.5 57.3 47.6 Example 2 10 × 20 10 × 40 400 297.5 360 509 0.100.18 0.14 26.1 60.0 44.7 Example 3  9 × 20 10 × 40 400 290 390 521 0.070.21 0.15 21.6 57.7 42.3 Example 4 10 × 20 10 × 40 400 400 331 531 0.070.23 0.14 32.5 55.8 43.1

EXAMPLE 6

The structures made according to the procedures described in Examples 1,2, 3, and 4 were tested for liquid acquisition properties. To evaluatethe acquisition properties, the Acquisition Time was measured, that isthe time, for a given volume of saline solution to be absorbed by anabsorbent structure (until any free liquid disappears from the surfaceof the absorbent).

The following method was used to measure the Acquisition Time:

1. Condition sample in lab at 70° F. and 50% relative humidity for 2hours prior to testing.

2. Prepare standard saline solution (0.9% NaCl/DI H₂0 by weight). Adddye if desired.

3. Determine insult volume and load to be used. Medium capacity samples(most diapers of medium size (size #3)) use 3×75 ml insults and 0.4-psiload. The absorbent structures described in Examples 1-4 belong to thiscategory.

4. If sample is formed in lab or on pilot machine (airlaid), cut torequired dimensions. This is 4 inches×14 inches for samples made on thelab pad former, 4 inch×16 inches for samples made on the pilot machine.If sample is a commercial diaper, simply cut elastic legbands so thatdiaper will lay flat. Take weight/thickness measurements of each sample.

5. Prepare airlaid samples by placing on plastic backsheet, ExxonEMB-685 polyethylene film, and adding coverstock material, 15 gsm Avgolspunbond polypropylene. Ensure that plastic backsheet material edgesfold up toward top of sample to protect against leakage while testing.

6. Place sample in acquisition apparatus by placing sample on bottomplate, positioning foam piece on top of sample, placing insult ring intohole in foam, and then positioning weighted top plates over foam piece.

7. Set timer for 20 minutes and place beside test apparatus.

8. With stopwatch in one hand and graduate cylinder containing insultvolume in other hand, prepare to insult sample. Pour fluid into insultring. Start stopwatch at moment the fluid strikes the sample. Emptyfluid from cylinder as quickly as possible. Stop stopwatch when fluid isabsorbed by sample.

9. Note time taken by sample to absorb fluid. Start 20 minute timer assoon as fluid is absorbed by sample.

10. After 20 minutes, repeat steps 7-9.

11. After another 20 minutes, repeat steps 7-9. Note: If no other testsare to be done after the Acquisition test, the 20-minute intervalfollowing the third insult can be omitted. However, if another test isto be done following the Acquisition test (Rewet and Retention orDistribution), the 20-minute interval must be used and then the othertest may be started.

The following formula is used to calculate the Acquisition Rate:${{Acquisition}\quad {Rate}\quad ( {{ml}/s} )} = \frac{{Insult}\quad {Volume}\quad ({ml})}{{Aquisition}\quad {Time}\quad (s)}$

The results obtained from testing the structures of Examples 1, 2, 3,and 4 are collected in Table 3. In Table 3 are summarized also theresults of the analysis of the absorbent cores of some commercial diaperarticles samples A, B and C and of another commercial diaper core,sample D, and having basic physical properties as described in Table 2.The data in Table 3 includes the results obtained from testing thestructures of Examples 1, 2, 3, and 4. The structures of these Exampleswere assembled according to the illustration in FIG. 1. The length ofthe Upper Plies in these structures was 20 cm in each case. The resultsin Table 3 indicate that absorbent structures of Examples 1, 2, 3, and 4have considerably shorter Acquisition Times than sample D. It can alsobe seen that the absorbent structures of Examples 3 and 4 have shorterAcquisition Times than those of the cores of all the tested commercialdiapers.

TABLE 3 1st 2nd 3rd Acquisition Acquisition Acquisition AbsorbentStructure Rate, ml/s Rate, ml/s Rate, ml/s Example 1 1.16 0.56 0.36Fxample 2 1.35 0.86 0.63 Example 3 2.85 1.29 0.93 Example 4 5.56 2.711.83 Example A 2.01 1.19 0.83 Example E 2.25 1.70 1.24 Example B 1.900.75 0.55 Example C 1.32 0.46 0.33 Example D 0.91 0.49 0.30

EXAMPLE 7

The structures made according to the procedures described in Examples 1,2, 3 and 4 were tested for rewet. In order to evaluate the rewet, theRewet was measured, that is the amount of liquid, which can be detectedon the surface of the absorbent structure after its saturation with agiven amount of saline.

The following method was used to measure Rewet:

The Rewet and Retention Test is designed to be performed immediatelyfollowing the Acquisition Test. The Acquisition Test procedure must befollowed before starting this test. If no acquisition information isneeded, acquisition times do not have to be recorded, however thepattern of 3 insults separated by 20-minute intervals must be followed.It is imperative that the 20 minute interval has elapsed before startingthis test. Sample/solution preparation is the same as in the Acquisitiontest (See Acquisition Test document).

1. Sample is now assumed to have been through the Acquisition Test andleft undisturbed for the final 20-minute time interval. Set a timer for5 minutes and place beside test apparatus.

2. Weigh stack of 10 Buckeye S-22 Blotter papers cut to same dimensionas sample.

3. Remove weight over sample, foam piece, and insult ring.

4. Place stack of papers on sample.

5. Replace foam piece and weights over sample. Start 5-minute timer.

6. At end of 5 minutes, remove weight and weigh stack of papers.

Note weight differences between wet and dries papers. The rewet iscalculated according to the formula:

Rewet (g)=Weight of wet papers (g)−weight of dry papers (g)

The following formula is used to calculate the Rewet Retention after thethird insult:${{Rewet}\quad {Retention}\quad (\%)} = \frac{\begin{matrix}{{{{Vol}.\quad {of}}\quad {All}\quad {Insults}\quad ({ml})} -} \\{( {{Rewet}\quad (g) \times 1\quad {ml}\text{/}g} ) \times 100}\end{matrix}}{{Volume}\quad {of}\quad {ALL}\quad {insults}\quad ({ml})}$

The structures of Examples 1, 2, 3, and 4 were tested for Rewet and theresults are presented in Table 4. The data in Table 3 includes theresults obtained from testing the structures of Examples 1,2,3 and 4.The structures of these Examples were assembled according to theillustration in FIG. 4. The length of the Upper Plies in thesestructures was 20 cm in each case. In Table 4 are summarized also theresults of the analysis of the absorbent cores of some commercial diaperarticles, samples A, B and C and of the commercial core, sample D, asdescribed in Table 2. The data in Table 4 indicate that except for theSample of Example E, had the lowest Rewet Retention value, all the othertested cores had Rewet Retention values at least 97%.

TABLE 4 Absorbent Structure Rewet Retention, % Example 1 97.0 Example 298.4 Example 3 99.4 Example 4 97.2 Example A 98.5 Example E 92.8 ExampleB 99.8 Example C 99.0 Example D 97.1

EXAMPLE 8

An absorbent structure was made by dry-forming on a DanWeb pilotmachine. The mechanical and absorbency properties of the structure aredepicted in Tables 5 and 6. The structure exhibited improved performancedue to the combination of appropriate levels of softness, pliability andwet integrity. Three forming heads were used to make the absorbentstructure. The product was laid on a carrier of Cellutissue 3024 havingbasis weight of 18 gsm. Prior to use, this tissue was impregnated with 4gsm bicomponent binder fiber, T-255 (Kosa Salisbury, N.C.), havingthickness of 2.8 denier per fiber. This fiber was deposited on thecarrier tissue on the DanWeb pilot machine and cured to bond thebicomponent fiber to the tissue. The purpose of this was to obtain agood adhesion of the carrier to the product formed on it. The carriertissue constituted the bottom stratum of the absorbent structure. Toconstruct the lower middle stratum, the first forming head of themachine was fed with 96 gsm ND416 fluff (Weyerhaeuser, Tacoma, Wash.)and 115 gsm superabsorbent polymer SXM70 (Stockhausen, Greensboro,N.C.). Then, during the process, the upper middle stratum was formed byfeeding the second forming head with 62 gsm of Foley Fluff (BuckeyeTechnologies, Memphis, Tenn.), 25 gsm of superabsorbent polymer SXM70,and 12 gsm of bicomponent binder fiber, T-255. Finally, the top stratumwas formed by feeding the third forming head with 42 gsm Wellman 376X2polyester fiber, of which the thickness was 15 denier per fiber and thelength was 6 mm. The top stratum was sprayed with 6 gsm of latex A-181(Air Products, Allentown, Pa.), at a concentration of 10% solids. Thesheet was compacted to the thickness of 2.6 mm and cured.

EXAMPLE 9

An absorbent structure was made by dry-forming on a DanWeb pilotmachine. The mechanical and absorbency properties of the structure aredepicted in Tables 5 and 6. The structure exhibited improved performancedue to the combination of appropriate levels of softness, pliability andwet integrity. Three forming heads were used to make the absorbentstructure. The bottom stratum was formed by feeding the first forminghead with 83 gsm Foley Fluff and 7 gsm bicomponent binder fiber T-255,having thickness of 2.1 denier per fiber. The middle stratum was formedby feeding the second forming head with 110 gsm Foley Fluff, 130 gsmsuperabsorbent polymer SP 1186 (Stockhausen, Greensboro, N.C.) and 15gsm bicomponent binder fiber T-255, having thickness of 2.1 denier perfiber. The top stratum was formed by feeding the third forming head with42 gsm Wellman 376X2 polyester fiber, of which the thickness was 15denier per fiber and the length was 6 mm. The top stratum was sprayedwith 8 gsm latex A-181, at a concentration of 10% solids. The sheet wascompacted to the thickness of 5.2 mm and cured.

EXAMPLE 10

An absorbent structure was made by dry-forming on a DanWeb pilotmachine. The mechanical and absorbency properties of the structure aredepicted in Tables 5 and 6. The structure exhibited improved performancedue to the combination of appropriate levels of softness, pliability andwet integrity. The product was laid on a carrier, which was Cellutissue3024 having basis weight of 18 gsm. Prior to use this tissue wasimpregnated with 4 gsm of bicomponent binder fiber, T-255, havingthickness of 2.8 denier per fiber. The carrier tissue constituted thebottom stratum of the absorbent structure. In order to construct thelower middle stratum, the first forming head was fed with ND416 fluff(Weyerhaeuser, Tacoma, Wash.) at 80 gsm, and superabsorbent polymerSXM70 at 100 gsm. The upper middle stratum was formed with the secondforming head by feeding it with Foley fluff at 79 gsm and superabsorbentpolymer SXM70 at 38 gsm. The top stratum was formed with the thirdforming head with Wellman 376X2 poly(ethylene terephtalate) having thethickness of 15 denier per fiber and the length of 6 mm. This fiber wasfed at 38 gsm. The product was sprayed from the top with an aqueoussolution of Kymene 557H wet strength resin (Hercules, Willmington, Del.)at 10% solids. The target basis weight of Kymene solids on the web was 7gsm. Due to the pressure gradient resulting from the difference betweenthe higher pressure at the top stratum of the formed structure and thelower pressure under the forming wire the solution of the bonding agentcould penetrate to some extent to the strata below, so the Kymene couldbond both the top stratum and the strata below. The product wascalandered to get the thickness of 2.6 mm.

EXAMPLE 11

An absorbent core was made by dry-forming on an M&J commercial machinewith three forming heads. The product was laid on a carrier, which wasCellutissue 3024 having basis weight of 18 gsm. The bottom stratum wasformed by feeding the first and the second heads with equal amounts ofND416 fluff, superabsorbent polymer SXM3950 (Stockhausen, Greensboro,N.C.) and bicomponent binder fiber T-255 having a thickness of 2.8denier per fiber. The composition of the bottom stratum thus formed, bytotal weight of this stratum, was 23.2% ND416, 48.2% SXM3950 and 2.6%T-255. The middle stratum was formed by feeding the third head withND416 at 38.1 gsm and T-255 at 9 gsm. The product thus formed was joinedwith Licontrol 381002-48, a 48 gsm synthetic nonwoven (Jacob HolmIndustries, Soultz, France), which constituted the top stratum of thestructure. The structure was analyzed for mechanical and absorbencyproperties. The results are depicted in Tables 5 and 6. The structureexhibited improved performance due to the combination of appropriatelevels of softness, pliability and wet integrity.

The structures of Examples 8-11 were analyzed for Wet Integrity,Softness and Pliability. The obtained results are summarized in Table 6.In Table 6 are also given the results of the tests carried out with anumber of commercial diaper cores. The data in Table 6 indicate thatabsorbent structures of Examples 8-11 have higher Wet Integrity, higherSoftness and higher Pliability than all the other tested absorbentcores.

TABLE 6 Wet Integrity Absorbent Structure mN/gsm Softness, 1/JPliability, 1/N Example 8 6.5 30.4 272.7 Example 9 12.3 37.5 235.5Example 10 8.1 22.1 259.9 Example 11 6.5 13.1 199.6 Example A 0.8 10.1175.5 Example E 4.2 12.4 196.7 Example B 2.6 12.9 137.8 Example C 1.57.4 47.7 Example D 1.3 5.6 40.2

EXAMPLE 13

The structures made according to the procedures described in Examples8-11 were tested for rewet according to the method described above inExample 7. as described. The results of the Rewet retention for thestructures of Examples 8-11 and an commercial absorbent core (Example E)are set forth in Table 7. It can be seen that the Rewet Retention valuesof the structures of Examples 8-11 are as good or better than the RewetRetention value for the commercial structure (Example E).

TABLE 7 Absorbent Structure Rewet Retention, % Example 1 97.3 Example 283.3 Example 3 98.3 Example 4 99.1 Example E 84.6

TABLE 5 Overall Overall Overall Overall average average average surfaceBasis core core area Weight Density % Sample (cm2) (gsm) (g/cc) SAPExample D 398 472 0.31 43.0 Example C 385 759 0.14 26.7 Example B 468617 0.25 53.5 Example E 260 547 0.11 44.9 Example A 360 649 0.26 43.4Example 8 320 380 0.15 36.8 Example 9 320 395 0.08 32.9 Example 10 320364 0.14 37.9 Example 11 320 387 0.21 58.1

What is claimed is:
 1. An absorbent structure having wet integrityhigher than about 4.0 mN/gsm, softness higher than 8.0/J, pliabilityhigher than about 70/N, and providing a substantially dryliquid-accepting surface after receiving a quantity of liquid, saidstructure comprising: a) an upper ply having an upper fluid receivingsurface and a lower surface and comprising: i) a top stratum comprisingsynthetic matrix fibers bonded with a binder, said matrix fibers havinglength from about 2 to about 15 mm; ii) a middle stratum in fluidcommunication with the top stratum, the middle stratum including naturalfibers, superabsorbent particles and a binder; and iii) a bottom stratumin fluid communication with the middle stratum, the bottom stratumincluding natural fibers and a binder; and b) a lower ply in fluidcommunication with the upper ply, the lower ply having an upper surfaceand a lower surface and including at least one stratum including naturalfibers, superabsorbent polymer particles, and a binder, wherein thelower surface of the upper ply has a surface area less than about 80% ofthe upper surface area of the lower ply; c) the basis weight of the topstratum of the upper ply is from about 20 gsm to about 120 gsm; d) thebinder content (per cent by weight) in the top stratum of the upper plyis from about 5% to about 20%; e) the basis weight of the middle stratumof the upper ply is from about 50 gsm to about 1000 gsm; f) the bindercontent (per cent by weight) in the middle stratum of the upper ply isfrom about 1% to about 10%; g) the basis weight of the bottom stratum ofthe upper ply is from about 10 gsm to about 150 gsm; h) the bindercontent (per cent by weight) in the bottom stratum of the upper ply isfrom about 5% to about 15%; i) the superabsorbent particle content (percent by weight) in the upper ply is lower than the content ofsuperabsorbent particles in the lower ply; j) apparent density of theupper ply is lower than the apparent density of the lower ply; k) thebasis weight of the lower ply is from about 100 gsm to about 1000 gsm;l) apparent density of the lower ply is about 0.15 g/cc to about 0.25g/cc; m) the binder content (per cent by weight) in the lower ply isfrom about 1% to about 8%; and n) the lower ply contains at least 30%superabsorbent particles of the basis weight of the lower ply.
 2. Anabsorbent structure having wet integrity higher than about 4.0 mN/gsm,softness higher than 8.0/J, pliability higher than about 70/N, andproviding a substantially dry liquid-accepting surface after receiving aquantity of liquid, said structure comprising: a) an upper ply having anupper fluid receiving surface and a lower surface and comprising: i) atop stratum comprising synthetic matrix fibers bonded with a binder,said matrix fibers having length from about 2 to about 15 mm; ii) amiddle stratum in fluid communication with the top stratum, the middlestratum including natural fibers, superabsorbent particles and a binder;and iii) a bottom stratum in fluid communication with the middlestratum, the bottom stratum including natural fibers and a binder; andb) a lower ply in fluid communication with the upper ply, the lower plyhaving an upper surface and a lower surface and including at least onestratum including natural fibers, superabsorbent polymer particles, anda binder, wherein the lower surface of the upper ply has a surface arealess than about 80% of the upper surface area of the lower ply.
 3. Theabsorbent structure of claim 1 wherein the length of the syntheticmatrix fibers is from about 4 to about 12 mm.
 4. The absorbent structureof claim 1 wherein the synthetic matrix fibers are from about 2 to about30 denier per fiber.
 5. The absorbent structure of claim 4 wherein thesynthetic matrix fibers are from about 6 to about 15 denier per fiber.6. The absorbent structure of claim 1 wherein the synthetic matrixfibers are selected from the group consisting of polyethylene,polypropylene, polyester, polyamide, cellulose acetate, rayon fibers,and mixtures thereof.
 7. The absorbent structure of claim 1 wherein thebinder is selected from the group consisting of latex binders,thermoplastic powders, thermoplastic fibers, bicomponent fibers andmixtures thereof.
 8. The absorbent structure of claim 1 wherein thebinder is selected from the group consisting of polyamide-polyamineepichlorohydrin adducts, cationic starch, dialdehyde starch, poly(vinylalcohol), chitosan and mixtures thereof.
 9. The absorbent structure ofclaim 1 wherein said natural fibers are selected from the groupconsisting of cotton, softwood pulps, hardwood pulps, straw, keaffibers, cellulose fibers modified by chemical, mechanical and/or thermaltreatments, keratin fibers, and mixtures thereof.
 10. The absorbentstructure of claim 1 wherein the basis weight of the top stratum of theupper ply is from about 30 gsm to about 60 gsm.
 11. The absorbentstructure of claim 1 wherein the content of synthetic matrix fibers inthe top stratum of the upper ply is from about 50 to about 99% byweight.
 12. The absorbent structure of claim 10 wherein the content ofsynthetic matrix fibers in the top stratum of the upper ply is fromabout 75 to about 90% by weight.
 13. The absorbent structure of claim 1wherein the basis weight of the middle stratum of the upper ply is fromabout 80 gsm to about 300 gsm.
 14. The absorbent structure of claim 1wherein the content of superabsorbent polymer particles in the middlestratum of the upper ply is from about 5 to about 60% by weight of theupper ply.
 15. The absorbent structure of claim 14 wherein the contentof superabsorbent polymer particles in the middle stratum of the upperply is from about 20 to about 50% by weight.
 16. The absorbent structureof claim 1 wherein the bottom stratum of the upper ply is an airlaidlayer.
 17. The absorbent structure of claim 1 wherein the bottom stratumof the upper ply is a wet-laid cellulose tissue.
 18. The absorbentstructure of claim 1 wherein the apparent density of the lower ply isfrom about 0.15 g/cc to about 0.25 g/cc.
 19. The absorbent structure ofclaim 1 wherein the basis weight of the lower ply is from about 150 gsmto about 400 gsm.
 20. The absorbent structure of claim 1 wherein thecontent of superabsorbent polymer particles in the lower ply is fromabout 30 to about 80% by weight.
 21. The absorbent structure of claim 20wherein the content of superabsorbent polymer particles in the lower plyis from about 40 to about 60% by weight.
 22. The absorbent structure ofclaim 1 wherein all layers of each ply are fully integrated in theforming process.
 23. The absorbent structure of claim 1 wherein each plyis airlaid.
 24. The structure of claim 1 wherein superabsorbent polymerparticles are placed in at least one of the strata of the upper ply inlongitudinal discrete lanes along the length of the core, said lanesincluding from about 70% to 100% superabsorbent polymer particles, andsaid lanes being separated by adjacent lanes including fibers and abinder.
 25. The structure of claim 1 wherein superabsorbent polymerparticles are placed in the lower ply in longitudinal discrete lanesalong the length of the core, said lanes including from about 70% to100% superabsorbent polymer particles, and said lanes being separated byadjacent lanes including fibers and a binder.
 26. An absorbent structurehaving wet integrity higher than about 4.0 mN/gsm, softness higher than8.0/J, pliability higher than about 70/N, and providing a substantiallydry liquid-accepting surface after receiving a quantity of liquid, thesaid structure comprising: a) an upper ply having an upper fluidreceiving surface and a lower surface comprising: i) a top stratumincluding synthetic matrix fibers bonded with a binder, said matrixfibers having length of from about 2 to about 15 mm; ii) a middlestratum in fluid communication with the top stratum, the middle stratumincluding natural fibers and superabsorbent polymer particles; and iii)a bottom stratum in fluid communication with the middle stratum,including natural fibers and a binder; b) and a lower ply in fluidcommunication with the upper ply, the lower ply having an upper surfaceand a lower surface and including: i) a top stratum including naturalfibers and a binder; and ii) a bottom stratum including natural fibers,superabsorbent polymer particles, and a binder, wherein: a) the lowersurface of the upper ply has a surface area less than about 80% of theupper surface area of the lower ply; b) the top stratum of the upper plyexhibits essentially no fluid wicking capability; c) the basis weight ofthe top stratum of the upper ply is from about 20 gsm to about 120 gsm;d) the binder content (per cent by weight) of the top stratum of theupper ply is from about 5% to about 20%; e) the basis weight of themiddle stratum of the upper ply is from about 50 gsm to about 1000 gsm;f) the binder content (per cent by weight) of the middle stratum of theupper ply is from about 1% to about 10%; g) the basis weight of thebottom stratum of the upper ply is from about 10 gsm to about 150 gsm;h) the binder content (per cent by weight) of the bottom stratum of theupper ply is from about 5% to about 15%; i) the content ofsuperabsorbent particles in the upper ply is lower than the content ofsuperabsorbent particles in the lower ply; j) the lower ply contains atleast 30% superabsorbent particles based on the total basis weight ofthe lower ply; k) the top stratum of the lower ply contains from about0% to about 20% superabsorbent particles based on the basis weight ofthe top stratum of the lower ply; l) the basis weight of the lower plyis from about 100 gsm to about 1000 gsm; m) the apparent density of thelower ply is about 0.15 g/cc to about 0.25 g/cc; n) the apparent densityof the upper ply is lower than the apparent density of the lower ply;and o) the binder content (per cent by weight) of the lower ply is fromabout 1% to about 8%.
 27. The absorbent structure of claim 26 whereinthe length of the synthetic matrix fibers is from about 4 to about 12mm.
 28. The absorbent structure of claim 26 wherein the synthetic matrixfibers are from about 2 to about 30 denier.
 29. The absorbent structureof claim 28 wherein the synthetic matrix fibers are from about 6 toabout 15 denier.
 30. The absorbent structure of claim 26 wherein thesynthetic matrix fibers are selected from the group consisting ofpolyethylene, polypropylene, polyester, polyamide, cellulose acetate,rayon, and mixtures thereof.
 31. The absorbent structure of claim 26wherein the binder is selected from the group consisting of latexbinders, thermoplastic powders, thermoplastic fibers, bicomponent fibersand mixtures thereof.
 32. The absorbent structure of claim 26 whereinthe binder is a water-soluble or water-dispersable bonding polymeragent.
 33. The absorbent structure of claim 26 wherein the naturalfibers are selected from the group consisting of cotton, softwood pulp,hardwood pulp, straw, keaf fibers, cellulose fibers modified bychemical, mechanical and/or thermal treatments, keratin and mixturesthereof.
 34. The absorbent structure of claim 26 wherein the basisweight of the top stratum of the upper ply is from about 30 gsm to about60 gsm.
 35. The absorbent structure of claim 26 wherein the content ofsynthetic matrix fibers in the top stratum of the upper ply is fromabout 50 to about 99% by weight.
 36. The absorbent structure of claim 26wherein the content of synthetic matrix fibers in the top stratum of theupper ply is from about 75 to about 90% by weight.
 37. The absorbentstructure of claim 26 wherein the basis weight of the middle stratum ofthe upper ply is from about 80 gsm to about 300 gsm.
 38. The absorbentstructure of claim 26 wherein the content of superabsorbent polymerparticles in the middle stratum of the upper ply is from about 5 toabout 60% by weight of the upper ply.
 39. The absorbent structure ofclaim 26 wherein the content of superabsorbent polymer particles in themiddle stratum of the upper ply is from about 20 to about 50% by weightof the upper ply.
 40. The absorbent structure of claim 26 wherein thebasis weight of the lower ply is from about 150 gsm to about 400 gsm.41. The absorbent structure of claim 26 wherein the overall content ofsuperabsorbent polymer particles in the lower ply is from about 30 toabout 80% by weight.
 42. The absorbent structure of claim 26 wherein thecontent of superabsorbent polymer particles in the lower ply is fromabout 40 to about 60% by weight.
 43. The absorbent structure of claim 26wherein the bottom stratum of the upper ply is airlaid.
 44. Theabsorbent structure of claim 26 wherein the bottom stratum of the upperply is a wet-laid cellulose tissue.
 45. The absorbent structure of claim26 wherein the basis weight of the top stratum of the lower ply is fromabout 10 gsm to about 150 gsm.
 46. The absorbent structure of claim 26wherein the basis weight of the top stratum of the lower ply is fromabout 15 gsm to about 90 gsm.
 47. The absorbent structure of claim 26wherein all strata in each ply are fully integrated in the formingprocess.
 48. The structure of claim 26 made by airlaid process.
 49. Thestructure of claim 26 wherein superabsorbent polymer particles areplaced in at least one of the strata of the upper ply in longitudinaldiscrete lanes along the length of the core, said lanes including fromabout 70% to 100% superabsorbent polymer particles, and said lanes beingseparated by adjacent lanes including fibers and a binder.
 50. Thestructure of claim 26 wherein superabsorbent polymer particles areplaced in at least in one stratum of the lower ply in longitudinaldiscrete lanes along the length of the core, said lanes including fromabout 70% to 100% superabsorbent polymer particles, and said lanes beingseparated by adjacent lanes including fibers and a binder.
 51. Anabsorbent structure comprising: a) an upper ply including: i) a topstratum including polyester matrix fibers bonded with latex in an amountof 15 to 25% by weight of said top stratum, said matrix fibers havinglength from about 4 mm to about 8 mm and having thickness from about 9to about 15 denier per fiber, the basis weight of said top stratum beingfrom about 40 to about 60 gsm; ii) a middle stratum in fluidcommunication with the top stratum, the middle stratum includingsoftwood fluff, superabsorbent polymer particles, and binder fiber, thecontent of the superabsorbent polymer particles being from about 30 to40% of the basis weight of the said middle stratum, the content of thebinder fibers being from about 6 to about 12% of the basis weight of thesaid middle stratum, and the basis weight of the said middle stratumbeing from about 150 to about 200 gsm; iii) a bottom stratum in fluidcommunication with the middle stratum, including softwood fluff andbinder fibers, the content of the binder fibers being from about 8 toabout 16% of the basis weight of the said bottom stratum, and the basisweight of the said bottom stratum being from about 60 to about 120 gsm;and b) a lower ply in fluid communication with the upper ply, the lowerply comprising: i) a top stratum including softwood fluff and binderfibers, the content of the binder fibers being from about 10 to about25% of the basis weight of the said top stratum, and basis weight beingfrom about 20 to about 60 gsm; ii) a bottom stratum including softwoodfluff, superabsorbent polymer particles, and binder fibers, the contentof the superabsorbent polymer particles being from about 50 to about 80%of the basis weight of the said bottom stratum, the content of thebinder fibers being from about 2 to 5% of the basis weight of the saidbottom stratum; and iii) cellulose tissue upon which the lower ply hasbeen formed, wherein: a) the upper ply is airlaid and has a surface areaadjacent to the lower ply, said surface area being from about 40 to 60%of the facing surface area of the lower ply; b) the density of the upperply is from about 0.05 to about 1.0 g/cc; c) the density of the lowerply is from about 0.15 to about 0.3 g/cc.
 52. An absorbent structurecomprising: a) an upper ply containing: i) a top stratum includingpolyester matrix fibers bonded with latex in an amount of 15 to 25% byweight of said top stratum, said matrix fibers having length from about4 mm to about 8 mm and having thickness from about 9 to about 15 denierper fiber, the basis weight of said top stratum being from about 40 toabout 60 gsm; ii) a middle stratum in fluid communication with the topstratum, the middle stratum including softwood fluff, superabsorbentpolymer particles, and binder fiber, the content of the superabsorbentpolymer particles being from about 40 to 60% of the basis weight of thesaid middle stratum, the content of the binder fibers being from about 6to about 12% of the basis weight of the said middle stratum, and thebasis weight of the said middle stratum being from about 200 to about280 gsm; iii) a bottom stratum in fluid communication with the middlestratum, including softwood fluff and binder fibers, the content of thebinder fibers being from about 8 to about 16% of the basis weight of thesaid bottom stratum, and the basis weight of the said bottom stratumbeing from about 60 to about 120 gsm; and b) a lower ply in fluidcommunication with the upper ply, the lower ply comprising: i) a topstratum including softwood fluff and binder fibers, the content of thebinder fibers being from about 10 to about 25% of the basis weight ofthe said top stratum, and basis weight being from about 20 to about 60gsm; ii) a bottom stratum including softwood fluff, superabsorbentpolymer particles, and binder fibers, the content of the superabsorbentpolymer particles being from about 40 to about 60% of the basis weightof the said bottom stratum, the content of the binder fibers being fromabout 2 to 5% of the basis weight of the said bottom stratum, and thebasis weight of the said bottom stratum being from about 200 to about350 gsm; and iii) cellulose tissue upon which the lower ply has beenformed, wherein: c) the upper ply is airlaid and has a surface areaadjacent to the lower ply, said surface area being from about 40 to 60%of the facing surface area of the lower ply; d) the density of the upperply is from about 0.05 to about 1.0 g/cc; e) the density of the lowerply is from about 0.15 to about 0.3 g/cc.
 53. An absorbent article forabsorbing body fluids, comprising the absorbent structure of claim 1sandwiched between a liquid pervious topsheet and liquid imperviousbacksheet.
 54. An absorbent article for absorbing body fluids,comprising the absorbent structure of claim 26 sandwiched between aliquid pervious topsheet and liquid impervious backsheet.
 55. Anabsorbent article for absorbing body fluids, comprising the absorbentstructure of claim 51 sandwiched between a liquid pervious topsheet andliquid impervious backsheet.
 56. An absorbent article for absorbing bodyfluids, comprising the absorbent structure of claim 52 sandwichedbetween a liquid pervious topsheet and liquid impervious backsheet. 57.An absorbent structure having wet integrity higher than about 6.0kN/gsm, softness higher than 8.0/J, pliability higher than about 70/N,and providing a substantially dry liquid-accepting surface afterreceiving a quantity of liquid, said structure comprising: c) a topstratum comprising synthetic matrix fibers bonded with a binder, saidmatrix fibers having length from about 2 to about 15 mm; d) a middlestratum in fluid communication with the top stratum, the middle stratumcomprising natural fibers, superabsorbent polymer particles and abinder; and e) a bottom stratum in fluid communication with the middlestratum, comprising natural fibers and a binder.
 58. The absorbentstructure of claim 57 wherein the synthetic matrix fibers are from about2 to about 30 denier per fiber.
 59. The absorbent structure of claim 58wherein the synthetic matrix fibers are from about 6 to about 15 denierper fiber.
 60. The absorbent structure of claim 57 wherein the syntheticmatrix fiber is selected from the group consisting of polyethylene,polypropylene, polyester, polyamide, cellulose acetate, rayon fibers andmixtures thereof.
 61. The absorbent structure of claim 57 wherein thebinder is selected from the group consisting of latex binders,thermoplastic powders, thermoplastic fibers, bicomponent fibers andmixtures thereof.
 62. The absorbent structure of claim 57 wherein thebinder is selected from the group consisting of polyamide-polyamineepichlorohydrine adducts, cationic starch, dialdehyde starch, poly(vinylalcohol), chitosan and mixtures thereof.
 63. The absorbent structure ofclaim 57 wherein the natural fibers are selected from the groupconsisting of cotton, softwood pulps, hardwood pulps, straw, keaffibers, cellulose fibers modified by chemical, mechanical and/or thermaltreatments, keratin fibers and mixtures thereof.
 64. The absorbentstructure of claim 57 wherein the basis weight of the top stratum isfrom about 20 gsm to about 120 gsm.
 65. The absorbent structure of claim64 wherein the basis weight of the top stratum is from about 30 gsm toabout 60 gsm.
 66. The absorbent structure of claim 57 wherein thecontent of synthetic matrix fibers in the top stratum is from about 50to about 99% by weight.
 67. The absorbent structure of claim 66 whereinthe content of synthetic matrix fibers in the top stratum is from about75 to about 90% by weight.
 68. The absorbent structure of claim 57wherein the basis weight of the middle stratum is from about 50 gsm toabout 1000 gsm.
 69. The absorbent structure of claim 68 wherein thebasis weight of the middle stratum of the upper ply is from about 80 gsmto about 300 gsm.
 70. The absorbent structure of claim 57 wherein thecontent of superabsorbent polymer particles in the middle stratum isfrom about 5 to about 60% by weight of the absorbent structure.
 71. Theabsorbent structure of claim 70 wherein the content of superabsorbentpolymer particles in the middle stratum is from about 20 to about 50% byweight.
 72. The absorbent structure of claim 57 wherein the bottomstratum is an airlaid layer.
 73. The absorbent structure of claim 57wherein the bottom stratum is a wet-laid cellulose tissue.
 74. Theabsorbent structure of claim 57 wherein all strata of the said structureare fully integrated in the forming process.
 75. The absorbent structureof claim 57 made by airlaid process.
 76. The structure of claim 57wherein superabsorbent polymer particles are placed at least in one ofthe strata in longitudinal discrete lanes along the length of the core,said lanes including from about 70% to 100% superabsorbent polymerparticles, and said lanes being separated by adjacent lanes includingfibers and a binder.
 77. An absorbent structure, comprising: i. a topstratum comprising polyester fibers bonded with latex in an amount of 15to 25% by weight of said top stratum, said matrix fibers having lengthfrom about 4 mm to about 8 mm and having thickness from about 9 to about15 denier per fiber, the basis weight of said top stratum being fromabout 40 to about 60 gsm; ii. a middle stratum in fluid communicationwith the top stratum, the middle stratum comprising softwood flufffiber, superabsorbent polymer particles, and binder fiber, the contentof the superabsorbent polymer particles being from about 30 to 40% ofthe basis weight of the said middle stratum, the content of the binderfibers being from about 6 to about 12% of the basis weight of the saidmiddle stratum, and the basis weight of the said middle stratum beingfrom about 150 to about 200 gsm; and iii. a bottom stratum in fluidcommunication with the middle stratum, comprising softwood fluff andbinder fibers, the content of the binder fibers being from about 8 toabout 16% of the basis weight of the said bottom stratum, and the basisweight of the said bottom stratum being from about 60 to about 120 gsm,wherein the density of the structure is from about 0.05 to about 0.3g/cc, and the structure has a wet integrity higher than about 6.0mN/gsm, softness higher than 8.0/J and pliability higher than about70/N.
 78. An absorbent structure, comprising: i. a top stratumcomprising polyester matrix fibers bonded with latex in an amount of 15to 25% by weight of said top stratum, said matrix fibers having lengthfrom about 4 mm to about 8 mm and having thickness from about 9 to about15 denier per fiber, the basis weight of said top stratum being fromabout 40 to about 60 gsm; ii. a middle stratum in fluid communicationwith the top stratum, the middle stratum comprising softwood flufffiber, superabsorbent polymer particles, and binder fiber, the contentof the superabsorbent polymer particles being from about 40 to 60% ofthe basis weight of the said middle stratum, the content of the binderfibers being from about 6 to about 12% of the basis weight of the saidmiddle stratum, and the basis weight of the said middle stratum beingfrom about 200 to about 280 gsm; and iii. a bottom stratum in fluidcommunication with the middle stratum, comprising softwood fluff andbinder fibers, the content of the binder fibers being from about 8 toabout 16% of the basis weight of the said bottom stratum, and the basisweight of the said bottom stratum being from about 60 to about 120 gsm,wherein the density of the said structure is from about 0.05 to about1.0 g/cc, and the structure has a wet integrity higher than about 6.0mN/gsm, softness higher than 8.0/J and pliability higher than about70/N.
 79. An absorbent article for absorbing body fluids, comprising theabsorbent structure of claim 57 sandwiched between a liquid pervioustopsheet and liquid impervious backsheet.